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Avalanche Danger Scale

How the scale works

The North American Avalanche Danger Scale is a five-level scale used to communicate the danger of avalanches to backcountry recreationists. The danger is a combination of the expected likelihood, size, and distribution of avalanches.

An Introduction to the North American Avalanche Danger Scale

North American Public Avalanche Danger Scale

Avalanche danger is determined by the likelihood, size, and distribution of avalanches. Safe backcountry travel requires training and experience. You control your risk by choosing when, where, and how you travel.
Danger level	Travel advice	Likelihood	Size and distribution
5 – Extreme	Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.	Natural and human-triggered avalanches certain.	Very large avalanches in many areas.
4 – High	Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.	Natural avalanches likely; human-triggered avalanches very likely.	Large avalanches in many areas; or very large avalanches in specific areas.
3 – Considerable	Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.	Natural avalanches possible; human-triggered avalanches likely.	Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.
2 – Moderate	Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.	Natural avalanches unlikely; human-triggered avalanches possible.	Small avalanches in specific areas; or large avalanches in isolated areas.
1 – Low	Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.	Natural and human-triggered avalanches unlikely.	Small avalanches in isolated areas or extreme terrain.

Avalanche danger is determined by the likelihood, size, and distribution of avalanches. Safe backcountry travel requires training and experience. You control your risk by choosing when, where, and how you travel.

5 – Extreme
Travel advice
Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood
Natural and human-triggered avalanches certain.
Size and distribution
Very large avalanches in many areas.
4 – High
Travel advice
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Likelihood
Natural avalanches likely; human-triggered avalanches very likely.
Size and distribution
Large avalanches in many areas; or very large avalanches in specific areas.
3 – Considerable
Travel advice
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.
Likelihood
Natural avalanches possible; human-triggered avalanches likely.
Size and distribution
Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.
2 – Moderate
Travel advice
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Likelihood
Natural avalanches unlikely; human-triggered avalanches possible.
Size and distribution
Small avalanches in specific areas; or large avalanches in isolated areas.
1 – Low
Travel advice
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Likelihood
Natural and human-triggered avalanches unlikely.
Size and distribution
Small avalanches in isolated areas or extreme terrain.

Download the danger scale graphic (PNG)

How the scale works

North American Public Avalanche Danger Scale

5 – Extreme

4 – High

3 – Considerable

2 – Moderate

1 – Low